Multi-level monolithic fabrication techniques have been used in the past for semiconductor devices in which impurities are diffused into silicon, germanium or other crystalline substrates, in which the substrates are in general non-conductive. However, especially for electromagnetic devices, there is a need for the provision of conductors within a conductive block in which the conductors are insulated from the block. One such application would be the fabrication of magnetic recording heads.
Magnetic recording heads have, in the past, involved the utilization of a comb-like core through which insulated wires are threaded. The utilization of the insulated wires provides for control of the magnetic head but poses the problem of manually or automatically threading the wires on the core which in general results in high manufacturing costs and less process control.
It will be appreciated that most electromagnetic devices utilize wound cores involving the separate formation of a core which is over-wound in some fashion with insulated or coated wire so as to establish the required electromagnetic function. While in the past it has been possible to form certain types of flat inductors on a substrate, it has been only with difficulty, if at all, that insulated metallic conductors have been embedded in a conductive substrate or material for any kind of three dimensionality or multi-layer configuration.
It will of course be appreciated that the ability to embed conductors which are insulated from themselves and from the surrounding conductive material has utility not only in magnetic recording heads, but also in computer storage devices. The resulting structure can also be used as a multi-conductor cable, or when properly configured, is a magnetic transducer, especially useful in rotary or linear encoders.
Of course, multi-level sets of conductors embedded in a metallic core may, when appropriately connected, form a three-dimensional coil-like structure occupying more than one plane. The ability to form such an inductor especially in a monolithic fashion, has far reaching advantages.